One reason suicide attacks are a relatively modern phenomenon is that they have been enabled by modern explosives and motor vehicle technology, and to a lesser degree by modern automatic weapons.

Assassination has always been possible, and the option to commit suicide by cop/soldier has always been there, but actually harming large numbers of people in a spectacular fashion is not easy without, at the very least, something like dynamite. Motor vehicles vastly amplify the killing power of explosives by making them mobile and relatively difficult to stop.

We live in an era where one well-motivated individual can, with some study and practice, become a destructive force vastly greater than was possible in the past. This makes a difference, and the rise of suicide tactics is at least in part a response to this new technology. The motivation has probably been there for hundreds of years, it's just the ability is newer.

In my opinion this has been part of the reason behind the end of outright colonial rule. Colonialism and Imperialism were just vastly more profitable when it was harder for the oppressed to fight back, when they had to form actual armed groups with training and tactics and expensive weaponry to accomplish anything.